383 Big-Block Engine Build

There are many performance questions that we all wonder about when it comes to our Mopars, and opinions on engine tuning issues or parts selection are like, well, let's just say everybody seems to have one. Ask any three people at your local cruise night which carburetor will work best on a 383 big-block Mopar, and you'll certainly get three different answers. So after reading some of these types of questions on our forums, we decided that when it comes to testing parts on a Mopar engine, there's nothing like an engine dynamometer to measure the results. With a limited budget, some used parts, and some help from Comp Cams, Summit Racing Equipment, and Auto Performance Engines, we decided to put together a 383 that we can use for some dyno testing.

Normally, an engine build requires research, budgeting, and planning, but in our case we decided to make do with as many of the used parts lying around the shop as possible. Having a used (but worn out) standard-bore 383 engine block that someone gave us, we looked through the inventory under the workbench and found a nice standard 383 steel crankshaft, along with a full set of .030-inch oversized cast, flat-top pistons, and factory connecting rods. Since the Chrysler 383 HP was the most widely produced performance engine from the sixties through end of production in 1971, we figure this will be a good combination for dyno testing.

To top our short-block, we'll use a set of factory 906 cylinder heads that have had the ports cleaned up, but don't have any extensive port work performed. The open chamber design of the cylinder head, combined with the flat-top pistons, will provide a compression ratio of just over 10:1. The engine will run on pump gas and should resemble many of the engines in our reader's cars. With the hard parts in place we made some phone calls to get the rest of the parts we'd need.

Summit Racing Equipment has a great website that's easy to navigate when looking for multiple parts during one visit. In no time, we had our rings, bearings, oil pump, gaskets and seals ordered, and decided to splurge on an Edlebrock 383 Victor single-plane intake manifold. We're basically building this engine with a budget in mind, but to enhance performance and more closely duplicate the engines in our reader's Mopars, we'll be installing an aftermarket intake manifold, headers, and a flat-tappet camshaft and related components from Comp Cams.

Of all the Mopar enthusiasts we know, even the cheapest of our friends knows the benefit of installing an aftermarket camshaft. We also think that factory stamped steel rocker gear is a handicap for a performance engine, so we made the decision to upgrade our rocker arms with Comp's Ultra-Pro Magnum roller rocker kit. This kit includes all the parts including the rocker shafts, and combined with Comp's ball-ball-end pushrods is much stronger than the factory rockers. With the flexibility of adjustable rockers, we chose Comp's PN 23-231-4 camshaft which features .502 intake/ .511 exhaust lift and 236 intake/242 exhaust duration. By ordering the cam in kit form, we saved money and got the lifters, matching springs, and cam lube from Comp.

With the necessary parts in the back of the truck, we drove to nearby Auto Performance Engines (APE) in central Florida to have our pieces cleaned and inspected so that they could perform the necessary machine work. Luckily, our components all checked OK and we needed nothing but to over-bore the cylinders to accommodate our .030-inch oversize pistons. We also had APE resize the rods and install our ARP bolts, as well as polish the crankshaft, perform a multi-angle valve job, and machine the heads for our dual valve springs. Since we installed larger pistons, we had the rotating assembly balanced at APE as well. Back at the shop, we bolted our engine together with the new parts from Summit and Comp and headed back to APE for some dyno testing.

As of this writing, our 383 is on the dyno and we have performed the camshaft break-in procedure and run the engine with a little load to seat the piston rings. After changing the oil, we made a short pull using one of APE's 750-cfm vacuum secondary shop carburetors and only 34 degrees of timing. The engine made 360 horsepower at 5,500 rpm and 380 lb/ft of torque. We're quite sure this engine has more in it, so be sure to follow the tuning and dyno testing of this 383 in future issues of Mopar Muscle to see how much power this mild 383 can make.

11/14<STRONG>9</STRONG> The Comp rockers require a ball-ball style pushrod, which is arguable less prone to failure than the ball-cup style utilized by other manufacturers. We used a Comp pushrod length checking tool to ensure we ordered the correct length pushrods.